JP2856053B2 - Secondary air supply device for V-type engine - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a secondary air supply device for a V-type engine mounted on a vehicle, and more particularly to a V-type engine configured to guide air to an exhaust path through a secondary air supply passage. And a secondary air supply device.

[0002]

2. Description of the Related Art Conventionally, automobiles are designed to detoxify and emit exhaust gas from an engine by various exhaust gas purification devices. However, the operating state of the engine fluctuates greatly, and exhaust gas is completely rendered harmless throughout the entire operating range. It is difficult to do so, and various exhaust purification devices are used in combination. In particular,
At the start of the engine, activation of the catalyst is delayed, exhaust gas purification efficiency is low, and harmful gases such as unburned gas are easily discharged.
In view of this, a warm-up catalyst, which is quickly activated, is provided in front of the main catalyst to make exhaust gas harmless when the engine is started. However, even with this warm-up catalyst, activation requires a required warm-up time, and sufficient exhaust gas harmlessness cannot be achieved until the warm-up catalyst is activated. Therefore, secondary air is supplied to the exhaust passage until the warm-up catalyst is activated in the early stage of the engine start, and H in the exhaust gas is supplied.
A secondary air supply device for reburning and detoxifying C and CO is known.

[0003] This secondary air supply device introduces secondary air into an exhaust port near an exhaust valve, reburns exhaust gas to make it harmless, activates the catalyst quickly, and makes the exhaust air-fuel ratio uniform to make the catalyst uniform. The purification efficiency can be improved. For example, as shown in FIG. 20, the V-type engine 1 provided with this secondary air supply device introduces intake air from the intake manifold 4 in the air space between banks into each cylinder of the left and right banks 2 and 3, and The exhaust gas generated in each of the cylinders 3 and 3 is exhausted from the exhaust manifolds 5 and 6 at both ends of the banks 2 and 3 via exhaust pipes (not shown). One ends of secondary air pipes 7 and 8 communicate with a part of the exhaust manifolds 5 and 6, and the other ends of the secondary air pipes 7 and 8 are joined via reed valves 9 and 10, respectively. Through the air pump 12. Air pump 1
2 is driven at a predetermined time while the engine is being driven, and is configured so that fresh air from the air cleaner 13 can be forcibly supplied to both exhaust manifolds 5 and 6.

[0004] Further, Japanese Patent Publication No. 222221/1990 discloses V
Disclosed is a structure in which an air intake and an air intake chamber of a secondary air supply passage are integrally formed on a constituent member of an intake manifold in a space between banks of a model engine. Here, a reed valve is mounted on the upper part of the air intake chamber, and a pipe-shaped secondary air supply passage extending from the air intake chamber via the reed valve is provided so as to cross over each of the banks 2 and 3. Both secondary air supply passages communicate with the respective branch passages of the exhaust manifolds 5 and 6. In this way, when each branch path becomes negative pressure, air is supplied into the exhaust gas, HC and CO which are untwisted gases are reburned, the exhaust air-fuel ratio is made uniform, and the purification efficiency of the catalyst downstream of the exhaust path is improved. It raises the temperature of the exhaust gas and further accelerates the activation of the catalyst.

[0005]

Problems to be Solved by the Invention However, FIG.
In the secondary air supply device, secondary air pipes 7 and 8 extending from the air pump 12 wrap around the left and right banks 2 and 3 respectively, and are connected to both exhaust manifolds 5 and 6 to increase the space required for piping of the secondary air pipes. Since the piping is relatively long and the number of bent portions is relatively large, the pressure loss is increased and the amount of secondary air introduced is relatively easily reduced. In addition, the number of backflow prevention means is relatively large here, and there are many problems in terms of cost and space. On the other hand, the secondary air supply device disclosed in Japanese Patent Publication No. 2-22211 utilizes the airspace between banks. In this case, too, the secondary air supply passage extending from the reed valve crosses over the banks 2 and 3. And the space required for the secondary air pipe is large, and the pipe is relatively long. SUMMARY OF THE INVENTION It is an object of the present invention to provide a secondary type V-type engine with good mountability that does not require a space for piping of a secondary air supply passage for introducing secondary air to an exhaust port near an exhaust valve around an engine body. An object of the present invention is to provide an air supply device.

[0006]

In order to achieve the above object, the present invention relates to a V-type engine, comprising: a secondary air supply passage in an intake manifold provided inside an intake manifold provided between V banks. A secondary air supply port provided near an exhaust port in the cylinder head, and a secondary air supply in the cylinder head connecting the secondary air supply passage in the intake manifold provided in the cylinder head and the secondary air supply port. And a supply passage.

[0007]

A secondary air supply passage in the intake manifold is provided inside the intake manifold located between the V banks at the center of the engine body, and exhaust gas is discharged to the vicinity of the exhaust port of each cylinder head located on the outer peripheral side of the engine body. A secondary air supply port that can be introduced into the exhaust passage is provided, and the secondary air supply port and the secondary air supply passage in the intake manifold are connected by a secondary air supply passage in the cylinder head provided inside each cylinder head. The pipe does not protrude outside the outer periphery of the engine body.

[0008]

FIG. 1 shows a V-type engine 20 provided with a secondary air supply device for a V-type engine as one embodiment of the present invention. This V-type engine 20 is a 6-cylinder 4-valve DOH
The engine is a C engine, and intake air can be introduced into each cylinder of the left and right banks 22 and 23 from an intake manifold 24 arranged in the air space between the banks, and the exhaust gas generated in each cylinder of each bank 22 and 23 is discharged to each of the banks 22 and 23. Can be discharged from the exhaust manifolds 25 and 26 on both side ends to the exhaust pipe side equipped with a catalyst (not shown). The intake manifold 24 disposed in the space between the left and right banks 22 and 23 has an upper flange 27 formed at the upper end thereof to be connected to a surge tank (not shown), and is connected to the left and right banks 22 and 23 at the lower left and right. A lower flange 28 (see FIG. 3) is formed. The six branch openings 29 of the upper flange 27 extend downward from the left and right banks, respectively. The three branch paths alternately bifurcated to the left and right pass through the left and right lower flanges 28 and the left and right banks 22. , 23 are connected to the intake port 30 of each cylinder.

A lower wall 31 is integrally formed between lower ends of a lower flange 28 connected to the left and right banks 22 and 23. The lower wall portion 31 is formed continuously in the longitudinal direction of the engine, and inside the lower wall portion 31, secondary air supply passages (hereinafter simply referred to as central passages) 32, 33 in the intake manifold, which are two long holes parallel to each other, are formed. . One end of the central path 32 is formed so as to communicate with a relay valve 34 with an air cut valve supported on the end of the lower wall 31, and one end of the other central path 33 is connected to the one central path 32. Communicated.
These two central passages 32 and 33 are formed to have a relatively large diameter so that secondary air can be introduced without pressure loss. Here, since the two central paths 32 and 33 are arranged side by side at a predetermined interval, an obstacle can be arranged in the gap. However, in some cases, both paths may be configured as a single path. The symbol a in FIG. 1 indicates a cup sealing that seals a portion opened when each flow path is formed.

A part of both central passages 32, 33 in the lower wall 31 is connected to the cylinder heads 35, 36 of the left and right banks 22, 23.
Secondary air supply passage 3 in the cylinder head formed inside
7, 38. That is, the secondary air supply passages 37 and 38 in the cylinder head are connected to the communication passages 371 and 381 communicating with some of the branch passages of the central passages 32 and 33, and these communication passages 37
1, 381 and distribution paths 372, 382 facing the exhaust ports 39 of the three cylinders in each bank.
It is composed of As shown in FIG. 3, each of the communication paths 371, 381 is formed so as to cross the left and right cylinder heads 35, 36. As shown in FIG. 2, each distribution path 372, 3
Reference numeral 82 denotes a secondary air supply which passes right above each exhaust port 39 and is formed to be long in the longitudinal direction of the cylinder head, and a portion opposed to each exhaust port 39 can spray air toward the exhaust valve EV.
Injection ports n as supply ports are respectively formed. In addition, although the injection port n here is formed only on one exhaust valve EV side of each cylinder, an injection port may be formed on both exhaust valve sides.

The relay valve 34 with an air cut valve shown in FIG. 1 has a check valve function and a function as an electromagnetic on-off valve.
Among them, when functioning as an electromagnetic on-off valve, the control is performed by the controller 40. An air pump 42 is connected to the valve via an air pipe 41.
Air is supplied to 2 via an air cleaner 43.
The controller 40 is a well-known electronic control means. The controller 40 detects the engine operation information by an appropriate means, and determines that the current operation area according to the engine operation information is in a preset secondary air supply area. The relay valve with cut valve 34 is turned on, the air pump 42 is operated to supply the secondary air to the exhaust port 39 of each cylinder, and the valve 34 is shut off when the operating range is deviated.

The secondary air supply device attached to the V-type engine shown in FIG. 1 is in an operation range where a relay valve 34 with an air cut valve controlled by a controller 40 is turned on, and the air from the air pump 42 is supplied to both central passages 32. , 33, the respective communication paths 371, 381 and the distribution paths 372, 382, can be forcibly injected into the exhaust gas from the respective injection ports n. For this reason, HC and CO in the exhaust gas are reburned at the exhaust port 39 to make the exhaust gas harmless and increase the exhaust temperature, or to make the exhaust air-fuel ratio uniform, thereby improving the purification efficiency of the catalyst. . In particular, it is not necessary to separately provide a space required for the piping of the secondary air supply passage around the engine body, so that the mountability can be improved. FIG. 4 shows a V-type engine 20a equipped with a secondary air supply device for a V-type engine as another embodiment of the present invention. The V-type engine 20a includes many components that are the same as those of the engine 20 of FIG. 1 except for the configuration of the secondary air supply passage in the intake manifold and the cylinder head. Is abbreviated.

The V-type engine 20a has central paths 32, 33 'parallel to each other as a secondary air supply passage in the intake manifold on the lower wall 31 thereof, and both paths are communicated by a central horizontal path 44. The secondary air supply passage in the cylinder head which communicates with both central passages 32, 33 'is provided at the central passages 32, 33'.
Communication paths 371, 381 and cylinder-to-cylinder communication paths 373, 383 communicating with the respective two branch paths of
1, 381, 373 and 383, each of which intersects at two places, and is composed of distribution paths 372 and 382 facing the exhaust ports 39 of the three cylinders in each bank. Each connection 37
1, 381 are provided at the rear end and front end of the left and right banks 22, 23, respectively, and the inter-cylinder communication paths 373, 383 are provided between the two front cylinders and between the two rear cylinders of the left and right banks 22, 23. Be deployed.

As described above, in the secondary air supply device of the V-type engine 20a shown in FIG.
Each of the two connecting paths 371, 381, 373,
383, the distribution paths 372, 382
The pressure loss difference between the cylinders due to the difference in the upper position can be eliminated.
The deviation of the secondary air distribution amount due to the difference in the length of the secondary air supply passage for each cylinder can be eliminated and made uniform, and the HC reduction effect as shown by the broken line in FIG. Solid line indicates the amount of HC in each cylinder when there is no secondary air supply device) for each cylinder. In particular, when the injection port n close to the central passages 32 and 33 'of the injection ports n of each cylinder is in the exhaust stroke, the secondary air is supplied to the injection ports n of other cylinders farther than the injection port n. May interfere with
In this case, a relatively large-capacity pump was required. In this manner, two communication paths 371, 381, 373, and 38 were used.
In the case where 3 is provided, there is no inconvenience described above, and at this point, the load on the air pump 42 can be relatively reduced.

For this reason, when the relay valve 34 with the air cut valve is turned on and the secondary air is forcibly injected into the exhaust gas from each of the injection ports n of each of the distribution paths 372 and 382,
HC and CO in the exhaust gas can be recombusted evenly at each exhaust port 39 to make the exhaust gas harmless and increase the exhaust temperature, or to make the exhaust air-fuel ratio uniform, thereby improving the purification efficiency of the catalyst. . 6 (a) and 6 (b) show the change characteristics of the HC emission amount when the vehicle equipped with the V-type engine 20a of FIG. 4 is run at a predetermined vehicle speed pattern by broken lines. Also in this case, the solid line shows the amount of HC emission when there is no secondary air supply device. As is clear from this, it is clear that the V-type engine 20a in FIG. 4 has a remarkable HC reduction effect immediately after the start of the engine. FIG. 7 shows a V-type engine 20b equipped with a secondary air supply device for a V-type engine as another embodiment of the present invention. The V-type engine 20b includes many components that are the same as the engine 20 of FIG. 1 except for the configuration of the secondary air supply passage in the intake manifold and the cylinder head. Is abbreviated.

The V-type engine 20b has on its lower wall 31 central paths 45, 46 parallel to each other as secondary air supply passages in the intake manifold, and both paths are four central cross paths 44a crossing the lower wall 31. , 44b, 44c, 44d. In particular, the central crossroads 44a, 44c
Of the cylinder head 35 of the left bank
The branch c at each end of the central crossways 44b and 44d communicates with the ends of the two communication paths 381 'and 383' of the right bank cylinder head 36. It is formed so that. Furthermore, these communication paths 37
The distribution path 372 intersects 1 ′, 373 ′ and the connection path 38
The distribution path 382 is formed so as to intersect 1 ′, 383 ′. Each connection path 371 ', 373', 381 ', 38
3 'is provided near the front and rear ends of the left and right cylinder heads 35 and 36, and is formed so as to cross the same. As shown in FIG. 8, each distribution path 372, 382 is connected to each exhaust port 39.
Are formed in the longitudinal direction of the cylinder head 35 so as to pass directly above the nozzles 35, and injection ports n capable of spraying air toward the exhaust valve EV are formed in portions facing the exhaust ports 39, respectively.

As described above, in the secondary air supply device of the V-type engine 20b shown in FIG.
For every 6, two communication paths 371, 381, 3
73, 383 are provided to eliminate the pressure loss difference between the cylinders, to eliminate and uniform the difference in the distribution amount of the secondary air, and to make the HC and the HC in the exhaust gas uniform at each exhaust port 39.
By reburning the CO, the exhaust gas can be made harmless and the exhaust temperature can be increased, or the exhaust air-fuel ratio can be made uniform, so that the purification efficiency of the catalyst can be improved. In particular, the central crossroads 44
a, 44b, 44c, and 44d can process the respective branch paths c facing each other in the same processing step, and each of the branch paths c has a communication path 371 ', 373',
The ends of 381 'and 383' communicate with each other, and there is no need to seal each branch c after processing. In this regard, the cost can be reduced by reducing the number of processing steps, the number of parts, and the number of assembly steps.

The V-type engine 20b shown in FIG. 7 has two communication paths 37 each for the left and right cylinder heads 35 and 36.
1 ', 381', 373 ', and 383', the communication paths 373 'and 383' of the left and right cylinder heads 35 and 36 were eliminated, and instead, the two in FIG. As shown by the dotted line, the inter-cylinder communication path 373 ", 3
A V-type engine 20b 'provided with 83 "(instead of the V-type engine 20b in FIG. 7 and not shown) may be configured. In this case, a specific example of the intake manifold 24 of the V-type engine 20b' 9 to 15 show the cylinder head 3 of the left bank of the left and right banks 22 and 23.
5 is shown in FIGS. 16 to 19. The intake manifold 24 has an upper flange 27 formed at an upper end thereof and connected to a surge tank (not shown), and a lower flange 2 connected to left and right cylinder heads 35 and 36 at lower left and right portions.
8 (see FIG. 11). Six branches 29 are formed in the upper flange 27, and each branch extends a branch path IM downward as shown in FIG. 12, and each of the three branches is divided into two parts alternately left and right. The branch path IM is configured to pass through the left and right lower flanges 28 and communicate with the intake ports 30 (see FIG. 17) of the left and right cylinder heads 35 and 36.

Here, a lower wall portion 31 is integrally formed between lower ends of a lower flange 28 connected to the left and right cylinder heads 35, 36. As shown in FIGS. 9 to 15, the lower wall portion 31 is formed continuously in the longitudinal direction of the cylinder head, and has two central passages 45 and 46 parallel to each other formed therein. Note that reference numeral 47 in FIG. 9 indicates an EGR passage,
Figure 12 exhaust gas recirculated to the fresh air outlet line IM from the jetting nozzle 471, as shown in, with the aim of NO _X reduction, reference numeral 48 as shown in FIG. 13 introduces a blow-by gas into the intake passage passage Well-known PCV valve (not shown)
Is communicated to.

As shown in FIG. 10, one end of the central passage 45 is bent upward to form an upward opening 451, and is formed at the same end so as to communicate with the relay valve 34 'with an air cut valve. . As shown in FIG. 11, the two central paths 45 and 46 are four central cross paths 44 that cross the lower wall 31.
a ', 44b', 44c ', 44d' communicate with each other, and the branch c at each end of the central crossways 44b ', 44d'
Are the two communication paths 37 of the cylinder head 35 in the left bank
3 ", 371" (see FIG. 16), and the branch c at each end of the central lateral paths 44b, 44d is an end of the two communication paths 381 ', 383 "of the cylinder head 36 of the right bank. Further, these communication paths 37 are formed.
The distribution path 372 intersects with the other end of 1 ', 373 ", and the distribution path 382 intersects with the other end of the communication path 381', 383". As shown in FIG. 16, each cylinder head 35 has a mounting hole 50 for a not-shown spark plug, a mounting hole 51 for a not-shown intake / exhaust valve, a mounting hole 52 for a lash adjuster not shown, and , Bearing 53 of intake and exhaust camshaft not shown
Etc. are formed, and the communication path 3 is located at a position where interference with them is avoided.
71 ′, 373 ″ and distribution path 372 are formed.

That is, each of the communication paths 371 ', 373', 38
1 ', 383' are provided near the front and rear ends of the left and right cylinder heads 35, 36, and are formed to cross the same.
As shown in FIG. 8, each of the distribution passages 372 and 382 is formed to be long in the longitudinal direction of the cylinder head 35 passing directly above each of the exhaust ports 39, and air is exhausted at a portion opposed to each of the exhaust ports 39. An injection port n that can be sprayed on the EV side is formed. As described above, the secondary air supply device of the V-type engine 20b 'described with reference to FIGS.
Similarly to the V-type engine 20b, the pressure loss difference between the cylinders can be eliminated, and the HC in the exhaust gas can be
CO can be reburned to make the exhaust gas harmless and increase the exhaust temperature, or the exhaust air-fuel ratio can be made uniform to improve the catalyst purification efficiency.
a ', 44b', 44c ', 44d' can process each branch c in the same processing step, and connect each branch c to each connection path 37.
1 ', 373 ", 381', 383", which does not require a seal for each branch c, thereby reducing the number of processing steps, the number of parts, and the cost by reducing the number of assembly steps.

[0022]

As described above, according to the present invention, the secondary air supply passage in the intake manifold in the intake manifold disposed between the V banks of the V-type engine and the secondary air supply passage provided near the exhaust port of the cylinder head are provided. Since the secondary air supply port is connected to the secondary air supply passage in the cylinder head provided inside the cylinder head, the secondary air supply pipe can be made relatively short.
In addition, since the secondary air supply pipe does not protrude from the outer periphery of the cylinder head, the mountability is improved.

[Brief description of the drawings]

FIG. 1 is a schematic configuration diagram of a main part of a V-type engine equipped with a secondary air supply device for a V-type engine as one embodiment of the present invention.

FIG. 2 is an enlarged sectional view taken along the line XX of FIG. 1;

FIG. 3 is a schematic partial side view of the V-type engine of FIG.

FIG. 4 is a schematic configuration diagram of a main part of a V-type engine equipped with a secondary air supply device as another embodiment of the present invention.

FIG. 5 is a characteristic diagram of the amount of HC emission of each cylinder of the V-type engine of FIG. 4;

6 (a) is a characteristic diagram of the HC emission amount of the V-type engine of FIG. 4, and FIG. 6 (b) is a change diagram of a vehicle speed.

FIG. 7 is a schematic diagram of a main part of a V-type engine equipped with a secondary air supply device as another embodiment of the present invention.

FIG. 8 is an enlarged sectional view taken along the line X′-X ′ of FIG. 7;

FIG. 9 is a plan view of an intake manifold of a V-type engine equipped with a secondary air supply device as another embodiment of the present invention.

FIG. 10 is a side view of the intake manifold of FIG. 9;

FIG. 11 is a bottom view of the intake manifold of FIG. 9;

FIG. 12 is a sectional view taken along line AA of FIG. 9;

FIG. 13 is a sectional view taken along line BB of FIG. 9;

FIG. 14 is a side view of the intake manifold of FIG. 9 as viewed from AA.

FIG. 15 is a side view of the intake manifold of FIG. 9 as viewed from BB.

FIG. 16 is a plan view of a cylinder head of a V-type engine equipped with a secondary air supply device as another embodiment of the present invention.

FIG. 17 is a side view of the cylinder head of FIG.

18 is a sectional view taken along line DD of FIG.

FIG. 19 is a sectional view taken along line CC of FIG. 16;

FIG. 20 is a schematic plan view of a V-type engine equipped with a conventional secondary air supply device.

[Explanation of symbols]

 20 V-type engine 24 Intake manifold 27 Upper flange 29 Branch port 30 Intake port 32 Central path 33 Central path 34 Relay valve with air cut valve 39 Exhaust port 371 Communication path 372 Communication path 373 'Communication path 373 Cylinder communication path 373 "cylinder Intermediate road 45 Central road 46 Central road n Injection port

Claims (1)

(57) [Claims] In a V-type engine, a secondary air supply passage in an intake manifold provided inside an intake manifold provided between V banks and a secondary air supply provided near an exhaust port in a cylinder head. A V-type engine having an inlet, a secondary air supply passage in the intake manifold provided in the cylinder head, and a secondary air supply passage in the cylinder head connecting the secondary air supply opening. Next air supply device.